The handling and safety aspects of injector devices, having a certain degree of automatic functions, as well as immediate accessibility in emergency situations are issues that attract a lot of attention when developing this type of device. These devices typically rely on compressive spring forces that are released during the triggering of the device to cause the injection. One issue with these automated injection devices is the potential for the user to experience a negative tactile feeling as the needle penetration step and/or injection sequence is completed. This is sometimes referred to as “kick-back” and is a result of the excess spring forces being transferred from the device to the injection site. A goal of designers of these rug delivery devices is to minimize or eliminate these forces from being transferred or felt by the user of the device.
One known auto-injection device is described in the co-owned U.S. Pub. No. 2005/0101919, however, whereby the injection can be activated by a push button, i.e. penetration and injection, but only when the front end of the injector is pressed against the injection site. It is designed as a kind of two-step operation where the order has to be: pressing the injector at the site and then depressing the button. This ensures that the injector cannot be accidentally activated by merely pushing the button nor even pushing the button and then pressing the front end. This device however has no features to eliminate or reduce the transfer of excess spring force at the completion of the penetration step and/or injection step.